Two players play one round of rock-paper-scissors. The catch: if either player just submits their move directly, the other can see it in the mempool and beat it. Commit-reveal solves this. First each player submits keccak256(move, salt, player) as a commit. After BOTH commits are in, each reveals their move and salt and the contract verifies the hash matches.

Example 1: Rock beats Scissors.

• P1 calls commit(keccak256(abi.encode(Move.Rock, salt1, P1)))
• P2 calls commit(keccak256(abi.encode(Move.Scissors, salt2, P2)))
• P1 calls reveal(Move.Rock, salt1)
• P2 calls reveal(Move.Scissors, salt2)
  winner == P1, settled == true

Example 2: Tie when both play the same move.

• P1 calls commit(keccak256(abi.encode(Move.Rock, salt1, P1)))
• P2 calls commit(keccak256(abi.encode(Move.Rock, salt2, P2)))
• P1 calls reveal(Move.Rock, salt1)
• P2 calls reveal(Move.Rock, salt2)
  winner == address(0), settled == true

Example 3: P2 cannot steal P1's reveal.

• P1 calls commit(keccak256(abi.encode(Move.Rock, salt1, P1)))
• P2 calls commit(someOtherHash)
• P2 calls reveal(Move.Rock, salt1)
  reverts HashMismatch